kernel/drivers/gpu/drm/amd/amdgpu/amdgpu_pll.c

   1 /*
   2  * Copyright 2014 Advanced Micro Devices, Inc.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20  * OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  */
  23 #include <drm/drmP.h>
  24 #include <drm/amdgpu_drm.h>
  25 #include "amdgpu.h"
  26 #include "atom.h"
  27 #include "atombios_encoders.h"
  28 #include <asm/div64.h>
  29 #include <linux/gcd.h>
  30
  31 /**
  32  * amdgpu_pll_reduce_ratio - fractional number reduction
  33  *
  34  * @nom: nominator
  35  * @den: denominator
  36  * @nom_min: minimum value for nominator
  37  * @den_min: minimum value for denominator
  38  *
  39  * Find the greatest common divisor and apply it on both nominator and
  40  * denominator, but make nominator and denominator are at least as large
  41  * as their minimum values.
  42  */
  43 static void amdgpu_pll_reduce_ratio(unsigned *nom, unsigned *den,
  44                                     unsigned nom_min, unsigned den_min)
  45 {
  46         unsigned tmp;
  47
  48         /* reduce the numbers to a simpler ratio */
  49         tmp = gcd(*nom, *den);
  50         *nom /= tmp;
  51         *den /= tmp;
  52
  53         /* make sure nominator is large enough */
  54         if (*nom < nom_min) {
  55                 tmp = DIV_ROUND_UP(nom_min, *nom);
  56                 *nom *= tmp;
  57                 *den *= tmp;
  58         }
  59
  60         /* make sure the denominator is large enough */
  61         if (*den < den_min) {
  62                 tmp = DIV_ROUND_UP(den_min, *den);
  63                 *nom *= tmp;
  64                 *den *= tmp;
  65         }
  66 }
  67
  68 /**
  69  * amdgpu_pll_get_fb_ref_div - feedback and ref divider calculation
  70  *
  71  * @nom: nominator
  72  * @den: denominator
  73  * @post_div: post divider
  74  * @fb_div_max: feedback divider maximum
  75  * @ref_div_max: reference divider maximum
  76  * @fb_div: resulting feedback divider
  77  * @ref_div: resulting reference divider
  78  *
  79  * Calculate feedback and reference divider for a given post divider. Makes
  80  * sure we stay within the limits.
  81  */
  82 static void amdgpu_pll_get_fb_ref_div(unsigned nom, unsigned den, unsigned post_div,
  83                                       unsigned fb_div_max, unsigned ref_div_max,
  84                                       unsigned *fb_div, unsigned *ref_div)
  85 {
  86         /* limit reference * post divider to a maximum */
  87         ref_div_max = min(128 / post_div, ref_div_max);
  88
  89         /* get matching reference and feedback divider */
  90         *ref_div = min(max(DIV_ROUND_CLOSEST(den, post_div), 1u), ref_div_max);
  91         *fb_div = DIV_ROUND_CLOSEST(nom * *ref_div * post_div, den);
  92
  93         /* limit fb divider to its maximum */
  94         if (*fb_div > fb_div_max) {
  95                 *ref_div = DIV_ROUND_CLOSEST(*ref_div * fb_div_max, *fb_div);
  96                 *fb_div = fb_div_max;
  97         }
  98 }
  99
 100 /**
 101  * amdgpu_pll_compute - compute PLL paramaters
 102  *
 103  * @pll: information about the PLL
 104  * @dot_clock_p: resulting pixel clock
 105  * fb_div_p: resulting feedback divider
 106  * frac_fb_div_p: fractional part of the feedback divider
 107  * ref_div_p: resulting reference divider
 108  * post_div_p: resulting reference divider
 109  *
 110  * Try to calculate the PLL parameters to generate the given frequency:
 111  * dot_clock = (ref_freq * feedback_div) / (ref_div * post_div)
 112  */
 113 void amdgpu_pll_compute(struct amdgpu_pll *pll,
 114                         u32 freq,
 115                         u32 *dot_clock_p,
 116                         u32 *fb_div_p,
 117                         u32 *frac_fb_div_p,
 118                         u32 *ref_div_p,
 119                         u32 *post_div_p)
 120 {
 121         unsigned target_clock = pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV ?
 122                 freq : freq / 10;
 123
 124         unsigned fb_div_min, fb_div_max, fb_div;
 125         unsigned post_div_min, post_div_max, post_div;
 126         unsigned ref_div_min, ref_div_max, ref_div;
 127         unsigned post_div_best, diff_best;
 128         unsigned nom, den;
 129
 130         /* determine allowed feedback divider range */
 131         fb_div_min = pll->min_feedback_div;
 132         fb_div_max = pll->max_feedback_div;
 133
 134         if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
 135                 fb_div_min *= 10;
 136                 fb_div_max *= 10;
 137         }
 138
 139         /* determine allowed ref divider range */
 140         if (pll->flags & AMDGPU_PLL_USE_REF_DIV)
 141                 ref_div_min = pll->reference_div;
 142         else
 143                 ref_div_min = pll->min_ref_div;
 144
 145         if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV &&
 146             pll->flags & AMDGPU_PLL_USE_REF_DIV)
 147                 ref_div_max = pll->reference_div;
 148         else
 149                 ref_div_max = pll->max_ref_div;
 150
 151         /* determine allowed post divider range */
 152         if (pll->flags & AMDGPU_PLL_USE_POST_DIV) {
 153                 post_div_min = pll->post_div;
 154                 post_div_max = pll->post_div;
 155         } else {
 156                 unsigned vco_min, vco_max;
 157
 158                 if (pll->flags & AMDGPU_PLL_IS_LCD) {
 159                         vco_min = pll->lcd_pll_out_min;
 160                         vco_max = pll->lcd_pll_out_max;
 161                 } else {
 162                         vco_min = pll->pll_out_min;
 163                         vco_max = pll->pll_out_max;
 164                 }
 165
 166                 if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
 167                         vco_min *= 10;
 168                         vco_max *= 10;
 169                 }
 170
 171                 post_div_min = vco_min / target_clock;
 172                 if ((target_clock * post_div_min) < vco_min)
 173                         ++post_div_min;
 174                 if (post_div_min < pll->min_post_div)
 175                         post_div_min = pll->min_post_div;
 176
 177                 post_div_max = vco_max / target_clock;
 178                 if ((target_clock * post_div_max) > vco_max)
 179                         --post_div_max;
 180                 if (post_div_max > pll->max_post_div)
 181                         post_div_max = pll->max_post_div;
 182         }
 183
 184         /* represent the searched ratio as fractional number */
 185         nom = target_clock;
 186         den = pll->reference_freq;
 187
 188         /* reduce the numbers to a simpler ratio */
 189         amdgpu_pll_reduce_ratio(&nom, &den, fb_div_min, post_div_min);
 190
 191         /* now search for a post divider */
 192         if (pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP)
 193                 post_div_best = post_div_min;
 194         else
 195                 post_div_best = post_div_max;
 196         diff_best = ~0;
 197
 198         for (post_div = post_div_min; post_div <= post_div_max; ++post_div) {
 199                 unsigned diff;
 200                 amdgpu_pll_get_fb_ref_div(nom, den, post_div, fb_div_max,
 201                                           ref_div_max, &fb_div, &ref_div);
 202                 diff = abs(target_clock - (pll->reference_freq * fb_div) /
 203                         (ref_div * post_div));
 204
 205                 if (diff < diff_best || (diff == diff_best &&
 206                     !(pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP))) {
 207
 208                         post_div_best = post_div;
 209                         diff_best = diff;
 210                 }
 211         }
 212         post_div = post_div_best;
 213
 214         /* get the feedback and reference divider for the optimal value */
 215         amdgpu_pll_get_fb_ref_div(nom, den, post_div, fb_div_max, ref_div_max,
 216                                   &fb_div, &ref_div);
 217
 218         /* reduce the numbers to a simpler ratio once more */
 219         /* this also makes sure that the reference divider is large enough */
 220         amdgpu_pll_reduce_ratio(&fb_div, &ref_div, fb_div_min, ref_div_min);
 221
 222         /* avoid high jitter with small fractional dividers */
 223         if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV && (fb_div % 10)) {
 224                 fb_div_min = max(fb_div_min, (9 - (fb_div % 10)) * 20 + 60);
 225                 if (fb_div < fb_div_min) {
 226                         unsigned tmp = DIV_ROUND_UP(fb_div_min, fb_div);
 227                         fb_div *= tmp;
 228                         ref_div *= tmp;
 229                 }
 230         }
 231
 232         /* and finally save the result */
 233         if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
 234                 *fb_div_p = fb_div / 10;
 235                 *frac_fb_div_p = fb_div % 10;
 236         } else {
 237                 *fb_div_p = fb_div;
 238                 *frac_fb_div_p = 0;
 239         }
 240
 241         *dot_clock_p = ((pll->reference_freq * *fb_div_p * 10) +
 242                         (pll->reference_freq * *frac_fb_div_p)) /
 243                        (ref_div * post_div * 10);
 244         *ref_div_p = ref_div;
 245         *post_div_p = post_div;
 246
 247         DRM_DEBUG_KMS("%d - %d, pll dividers - fb: %d.%d ref: %d, post %d\n",
 248                       freq, *dot_clock_p * 10, *fb_div_p, *frac_fb_div_p,
 249                       ref_div, post_div);
 250 }
 251
 252 /**
 253  * amdgpu_pll_get_use_mask - look up a mask of which pplls are in use
 254  *
 255  * @crtc: drm crtc
 256  *
 257  * Returns the mask of which PPLLs (Pixel PLLs) are in use.
 258  */
 259 u32 amdgpu_pll_get_use_mask(struct drm_crtc *crtc)
 260 {
 261         struct drm_device *dev = crtc->dev;
 262         struct drm_crtc *test_crtc;
 263         struct amdgpu_crtc *test_amdgpu_crtc;
 264         u32 pll_in_use = 0;
 265
 266         list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
 267                 if (crtc == test_crtc)
 268                         continue;
 269
 270                 test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
 271                 if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
 272                         pll_in_use |= (1 << test_amdgpu_crtc->pll_id);
 273         }
 274         return pll_in_use;
 275 }
 276
 277 /**
 278  * amdgpu_pll_get_shared_dp_ppll - return the PPLL used by another crtc for DP
 279  *
 280  * @crtc: drm crtc
 281  *
 282  * Returns the PPLL (Pixel PLL) used by another crtc/encoder which is
 283  * also in DP mode.  For DP, a single PPLL can be used for all DP
 284  * crtcs/encoders.
 285  */
 286 int amdgpu_pll_get_shared_dp_ppll(struct drm_crtc *crtc)
 287 {
 288         struct drm_device *dev = crtc->dev;
 289         struct drm_crtc *test_crtc;
 290         struct amdgpu_crtc *test_amdgpu_crtc;
 291
 292         list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
 293                 if (crtc == test_crtc)
 294                         continue;
 295                 test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
 296                 if (test_amdgpu_crtc->encoder &&
 297                     ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
 298                         /* for DP use the same PLL for all */
 299                         if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
 300                                 return test_amdgpu_crtc->pll_id;
 301                 }
 302         }
 303         return ATOM_PPLL_INVALID;
 304 }
 305
 306 /**
 307  * amdgpu_pll_get_shared_nondp_ppll - return the PPLL used by another non-DP crtc
 308  *
 309  * @crtc: drm crtc
 310  * @encoder: drm encoder
 311  *
 312  * Returns the PPLL (Pixel PLL) used by another non-DP crtc/encoder which can
 313  * be shared (i.e., same clock).
 314  */
 315 int amdgpu_pll_get_shared_nondp_ppll(struct drm_crtc *crtc)
 316 {
 317         struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
 318         struct drm_device *dev = crtc->dev;
 319         struct drm_crtc *test_crtc;
 320         struct amdgpu_crtc *test_amdgpu_crtc;
 321         u32 adjusted_clock, test_adjusted_clock;
 322
 323         adjusted_clock = amdgpu_crtc->adjusted_clock;
 324
 325         if (adjusted_clock == 0)
 326                 return ATOM_PPLL_INVALID;
 327
 328         list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
 329                 if (crtc == test_crtc)
 330                         continue;
 331                 test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
 332                 if (test_amdgpu_crtc->encoder &&
 333                     !ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
 334                         /* check if we are already driving this connector with another crtc */
 335                         if (test_amdgpu_crtc->connector == amdgpu_crtc->connector) {
 336                                 /* if we are, return that pll */
 337                                 if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
 338                                         return test_amdgpu_crtc->pll_id;
 339                         }
 340                         /* for non-DP check the clock */
 341                         test_adjusted_clock = test_amdgpu_crtc->adjusted_clock;
 342                         if ((crtc->mode.clock == test_crtc->mode.clock) &&
 343                             (adjusted_clock == test_adjusted_clock) &&
 344                             (amdgpu_crtc->ss_enabled == test_amdgpu_crtc->ss_enabled) &&
 345                             (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID))
 346                                 return test_amdgpu_crtc->pll_id;
 347                 }
 348         }
 349         return ATOM_PPLL_INVALID;
 350 }